The invention relates to ultrasonic methods, compositions and devices, particularly methods, compositions and devices that provide for multiple angle interrogation with ultrasonic transducer(s) over an anatomical region.
Ultrasonic techniques are often used as methods free of ionizing radiation for non-invasive assessment of anatomy, such as skeletal status in patients with osteoporosis. Quantitative aspects of these ultrasonic techniques can permit assessment of bone mass and density, as well as bone structure. Ultrasonic techniques for evaluating skeletal status also include measurements of speed of sound (xe2x80x9cSOSxe2x80x9d) that reflect the transmission velocity of ultrasonic waves passing through bone tissue and soft tissue, measurements of broadband ultrasonic attenuation (xe2x80x9cBUAxe2x80x9d) that assess the frequency dependence of ultrasonic attenuation, and pulse echo techniques that measure the energy scattered from the internal structure of the bone.
Many different measurement sites have been proposed for osteoporosis, such as the tibia, the patella, the phalanges, or the calcaneus. The calcaneus is preferred for quantitative ultrasonic measurements of skeletal status. It is composed of predominantly trabecular bone with only a thin cortical bone envelope medially and laterally, which together provide an excellent medium for detecting changes in SOS and BUA measurements. The calcaneus also permits convenient ultrasonic interrogation for the operator and the patient alike.
Although a number of commercial devices exist for diagnosis of osteoporosis, clinicians have recognized the limitations of such devices and methods. Correlations between quantitative ultrasonic measurements and assessments of bone mineral density using quantitative computed tomography, dual x-ray absorptiometry, and single photon absorptiometry have been reported to be poor at the calcaneus, as well as at other sites.
In addition, ultrasonic measurements of tissue, particularly in the calcaneus, often suffer from heterogenous tissue structures. Such structures as described herein can interfere with interrogation, which leads to deceased accuracy and precision of such measurements.
Consequently, the inventors have recognized the need, among other things, to provide reliable ultrasonic devices and accurate, and qualitative or quantitative methods for ultrasonic measurements in the diagnosis of osteoporosis, as well as methods and devices to generally improve diagnostic tools based on ultrasonic measurements. The methods and devices provide herein permit, among other things, correction of ultrasonic parameters, such as speed of sound and broadband ultrasonic attenuation, for soft tissue structures interposed in the ultrasonic beam and tissue heterogeneity and variations.
While many of the embodiments of the invention will find particular application in clinical measurements, such as BUA or SOS, and surgical procedures, such trocar procedures and catheter procedures, the invention provides for general ultrasonic devices and methods that will be applicable to many clinical applications.
The invention includes an ultrasonic system for multiple transmission angle ultrasonic interrogation in tissues with heterogenous structures that alter ultrasonic properties. The system can comprise a first ultrasonic transducer with an axis of transmission in common with a second ultrasonic transducer, said axis of transmission is through a portion of tissue suspected of having heterogenous structures that alter ultrasonic properties. The system can include an x, y positioner that can engage the first ultrasonic transducer and the second ultrasonic transducer. The x, y positioner controllably 1) positions the first ultrasonic transducer and the second ultrasonic transducer in a desired manner between at least a first and a second position while generally maintaining the axis of transmission and 2) establishes predetermined transmission angles for the first ultrasonic transducer and the second ultrasonic transducer to interrogate the portion of the tissue at multiple transmission angles through heterogenous structures in the tissue. A computational unit can be included that is designed to manage ultrasonic signal transmission and reception of the first ultrasonic transducer and the second ultrasonic transducer with either BUA or SOS or both. It may optionally be designed to control movement of the x, y positioner. The ultrasonic measurements with multiple transmission angles are typically improved compared to interrogation in the absence of multiple transmission angles.
In addition, the invention includes an ultrasonic system for automated ultrasonic measurements at multiple transmission angles. The system comprises an ultrasonic transducer unit comprising 1) an ultrasonic transducer that can transmit and receive signals and 2) a multiple transmission angle positioner to vary the transmission angle of the ultrasonic transducer with respect to the plane of a tissue in a predetermined fashion. Preferably, the transducer unit is designed to vary the transmission angle without necessarily changing the general position of the ultrasonic transducer with respect to the tissue. This allows the substantially same region to be interrogated at different angles. The system can include a computational unit designed to manage ultrasonic signal transmission and reception of the ultrasonic transducer unit and to process signals from the ultrasonic transducer unit at multiple transmission angles, for example using signal averaging, filtering unwanted signals or pattern recognition of desired types of acoustic signatures. Preferably, the computational unit is designed to process received ultrasonic signals from the ultrasonic transducer to generate at least one data set of an ultrasonic property determined at predetermined, multiple transmission angles. Such an ultrasonic property can be selected from the group consisting of broadband ultrasonic attenuation, echogenicity, reflective surfaces, distances from the transducer unit, speed of sound, and ultrasonic images.
In addition, the invention includes an ultrasonic system for tissue ultrasonic interrogation for broadband ultrasonic attenuation at multiple transmission angles. The system comprises a first ultrasonic transducer with an axis of transmission through an anatomical region to be interrogated and the first ultrasonic transducer is adapted for BUA and a second ultrasonic transducer adapted for BUA with the axis of transmission through the anatomical region to be interrogated, wherein monitoring broadband ultrasonic attenuation between the first ultrasonic transducer and the second ultrasonic transducer is permitted. The system includes a positioning unit to vary the transmission angle of the axis of transmission with respect to the tissue plane. The system may have a computational unit designed to manage ultrasonic signal transmission of the first ultrasonic transducer, to manage ultrasonic signal reception of the second ultrasonic transducer and to control the transmission angle of the axis of transmission. Typically, the positioning unit comprises an x,y positioner for the first ultrasonic transducer and the second ultrasonic transducer that can establish at least 3 predetermined transmission angles while maintaining a common axis of transmission. Preferably, the x,y positioner is designed to position the first ultrasonic transducer and the second ultrasonic transducer with first axis of transmission at each transmission angle generally passing through the same anatomical region. Typically, the center of axis of transmission at each angle passes through an area of the anatomical region that is no more than about 5 to 8 cm squared.
The invention also includes an ultrasonic method for ultrasonic interrogation at multiple transmission angles. The method comprises positioning, with respect to an anatomical region, an ultrasonic transducer unit comprising either 1) a first ultrasonic transducer that can transmit and receive signals or 2) a pair of ultrasonic transducers where a first member of the pair is designed to transmit signals and a second member of the pair is designed to receive signals. The methods includes interrogating the anatomical region with the ultrasonic transducer unit at predetermined, multiple transmission angles, and recording an ultrasonic property of the anatomical region. The method further comprises storing the ultrasonic property in a storage device.
The invention also includes an ultrasonic method for determining broadband ultrasonic attenuation or speed of sound measurements in dense tissues. The method comprises interrogating a tissue at predetermined, multiple transmission angles with an ultrasonic transducer unit adapted for either 1) broadband ultrasonic attenuation or 2) speed of sound measurements or both. The method includes determining dense tissue broadband ultrasonic attenuation, dense tissue speed of sound or both at two or more predetermined, multiple transmission angles, wherein the determining step generates a dense tissue broadband ultrasonic attenuation value, dense tissue speed of sound value or both that is more indicative of broadband ultrasonic attenuation or speed of sound in dense tissue than interrogation in the absence of predetermined, multiple transmission angles.
The invention also includes an ultrasonic method for generating an anatomic landmark for ultrasonic interrogation of an anatomical region, comprising:
positioning, if necessary, on the surface of a patient, with respect to an anatomical region, an ultrasonic transducer unit comprising either 1) a first ultrasonic transducer that can transmit and receive signals or 2) a pair of ultrasonic transducers wherein a first member of the pair is designed to transmit signals and a second member of the pair is designed to receive signals, and
interrogating the anatomical region with the ultrasonic transducer unit at a first transmission angle,
interrogating the anatomical region with the ultrasonic transducer unit at a second transmission angle,
identifying an anatomic landmark in common with the signals obtained in the above steps in the anatomical region with an ultrasonic property of the anatomical region.
The invention also includes an ultrasonic method for determining broadband ultrasonic attenuation or speed of sound measurements in dense tissues, comprising:
interrogating a patient""s tissue with at least a first ultrasonic transducer unit at a first transmission angle and a second ultrasonic transducer unit at a second transmission angle, wherein said first ultrasonic transducer unit and said second ultrasonic transducer unit are a) adapted for either 1) broadband ultrasonic attenuation or 2) speed of sound measurements or both and b) have an angle of least about 150 degrees between said first ultrasonic transducer unit and said second transducer unit,
interrogating said patient""s tissue with said first ultrasonic transducer unit at a third transmission angle and said second ultrasonic transducer unit at a fourth transmission angle while maintaining an angle of at least about 150 degrees between said first transducer unit and said second transducer unit, and
determining dense tissue broadband ultrasonic attenuation, dense tissue speed of sound or both for said tissue; wherein said determining step generates a dense tissue broadband ultrasonic attenuation value, dense tissue speed of sound value or both that is more indicative of broadband ultrasonic attenuation or speed of sound in dense tissue than in the absence of interrogating said patient""s tissue with at least said first ultrasonic transducer unit at a third transmission angle and said second ultrasonic transducer unit at a fourth transmission angle.
The invention also includes an ultrasonic system for determining broadband ultrasonic attenuation or speed of sound measurements in a tissue, comprising:
a transducer unit comprising at least a first ultrasonic transducer engaged with a first multiple transmission angle unit to controllably vary first transmission angles and a second ultrasonic transducer engaged with a second multiple transmission angle unit to controllably vary second transmission angles, wherein the first ultrasonic transducer unit and the second ultrasonic transducer unit are adapted for either 1) broadband ultrasonic attenuation or 2) speed of sound measurements or both, and
a computational unit for controllably adjusting transmission angles of the first and second transducer; wherein the ultrasonic system will measure broadband ultrasonic attenuation value, speed of sound value or both if so desired.
The invention also includes a computer program product, comprising:
instructions for a positioning unit to vary the transmission angle of a transducer or plurality of transducers at a plurality of transmission angles in an anatomical region,
instructions for interrogating the anatomical region with the transducer or the plurality of transducers at the plurality of transmission angles, and
instructions for recording at least one ultrasonic property at the plurality of transmission angles, wherein the above instructions facilitates a clinically relevant measurement and such instructions are stored on a computer retrievable medium.